Determination Of Thiobarbituric Acid Reactive Substances Research Articles

Hemolysis, icterus and lipemia interfere with the determination of two oxidative stress biomarkers in canine serum

BackgroundOxidative stress has been proven to play a role in numerous human and canine diseases. Among the biomarkers of oxidative stress, Thiobarbituric Acid Reactive Substances (TBARS) and Total Antioxidant Status (TAS) are two of the most widely used. Preanalytical factors are crucial for obtaining accurate results in these assays. Hemolysis, icterus and lipemia (HIL) are common sources of preanalytical errors in the laboratory; however, limited information is available regarding the considerations for canine specimens. Therefore, the objective of this study was to evaluate the potential interferences of HIL in the determination of TBARS and TAS in canine serum.MethodsSolutions of pooled canine serum samples were prepared by adding increasing concentrations of hemolysate, bilirubin and a synthetic lipid emulsion. TBARS and TAS were determined, and biases from the control value caused by the interfering substances were calculated.ResultsHemolysis, icterus and lipemia induced significant interferences on TBARS and TAS, albeit to varying degrees depending on the specific biomarker and interfering substance. TBARS appeared to be more susceptible to interferences in this study. Slight hemolysis, moderate icterus and slight lipemia caused notable deviations in TBARS values, surpassing the acceptable threshold for interference. TAS assay was also affected by HIL, although to a lesser extent compared to TBARS. Significant biases from TAS control value were observed when icterus was moderate, and when hemolysis and lipemia were more pronounced.ConclusionsIn light of our results, we conclude that hemolyzed, icteric and lipemic specimens are not suitable for TBARS and TAS determination in canine serum. Our findings hold considerable practical utility, as a simple visual inspection would be sufficient for identifying and excluding such specimens.

Synthesis and evaluation of the anticancer activity of bischalcone analogs in human lung carcinoma (A549) cell line

Bischalcone has gained much attention because of its wide range of application in pharmaceutical chemistry. This work aims to evaluate the antiproliferation effects and explore the anticancer mechanism of bischalcone analogs on human lung cancer A549 cells. In this study, we synthesized a series of bischalcone analogs via Aldol condensation reaction; MTT method was used to evaluate the antiproliferation effects; the 2′,7′-dichlorofluorescein fluorescence assay was used to determine the intracellular reactive oxygen species levels; the glutathione reductase-DTNB recycling assay was used to detect the redox imbalance; determination of thiobarbituric acid-reactive substance was used to evaluate the lipid peroxidation; Rhodamine 123 was used to test the mitochondrial membrane potential (MMP); the FITC/PI kit was used to detect the apoptosis; Western blotting was used to detect the expression of Bax and Caspase 3. After treatment with curcumin and bischalcone analogs, compounds 1d and 1g, the more stabilities compounds than curcumin, exhibited much higher potency in A549 cells than curcumin and other bischalcone analogs. Further mechanism of action studies revealed that 1d and 1g exhibited more stronger reactive oxygen species production abilities than curcumin and accompanied by the redox imbalance, lipid peroxidation, the loss of MMP, the activition of Bax and Caspase 3, and ultimately resulted in apoptosis of A549 cell. These data suggest that enhancing the reactive oxygen species generation ability of bischalcone analogs may be a promising strategy for the treatment of human lung cancer.

Oxidative Status Profile in Different Tissues of Parastacus brasiliensis promatensis (Crustacea, Decapoda, Parastacidae) over a Seasonal Cycle.

The objective of this study was to assess annual redox balance by quantifying activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST), as well as measuring lipid peroxidation levels by determination of thiobarbituric acid-reactive substances, in different tissues of male and female crayfish collected from an area little affected by anthropogenic impacts. A total of 37 male and 32 female of Parastacus brasiliensis promatensis were collected over an annual cycle, and gill, muscle, hepatopancreas, and gonad samples were harvested and subjected to the aforementioned analyses via spectrophotometry. Comparison of the annual oxidative status response profile in gill and in hepatopancreas between males and females revealed differences only in SOD activity. In abdominal muscle, this comparison revealed a distinct profile of SOD and GST activity, as well as of lipid peroxidation. SOD activity in gonads of females increased in the summer when compared to autumn; conversely, CAT and GST levels did not differ over the year. During reproduction, a possible increase of the energy requirements led to an increase in lipid peroxidation in all tested tissues, in males and females alike. It was least evident in female gonad tissue, which suggests this tissue type is relatively protected; within this context, one may establish a tissue-specific grading of Lipid Peroxidation intensity in females of the species during the spring: gonads < muscle < gills < hepatopancreas. Our results show that the responses of the defenses analyzed antioxidants, as well as lipid peroxidation levels, were sex and tissue dependent and a clear pattern of seasonal variation.

Biomarkers of oxidative damage and antioxidant defense capacity in Caiman latirostris blood

Several xenobiotics, and among them pesticides, can produce oxidative stress, providing a mechanistic basis for their observed toxicity. Chronic oxidative stress induces deleterious modifications to DNA, lipids and proteins that are used as effective biomarkers to study pollutant-mediated oxidative stress. No previous report existed on the application of oxidative damage and antioxidant defense biomarkers in Caiman latirostris blood, while few studies reported in other crocodilians were done in organs or muscles of dead animals. The aim of this study was to characterize a new set of oxidative stress biomarkers in C. latirostris blood, through the modification of conventional techniques: 1) damage to lipids by thiobarbituric acid reactive substances (TBARS), 2) damage to DNA by comet assay modified with the enzymes FPG and Endo III, and 3) antioxidant defenses: catalase, superoxide dismutase and glutathione; in order to apply them in future biomonitoring studies. We successfully adapted standard procedures for CAT, SOD, GSH and TBARS determination in C. latirostris blood. Calibration curves for FPG and Endo III showed that the three dilutions tested were appropriate to conduct the modified comet assay for the detection of oxidized bases in C. latirostris erythrocytes. One hour of incubation allowed a complete repair of the damage generated. The incorporation of these biomarkers in biomonitoring studies of caiman populations exposed to xenobiotics is highly important considering that this species has recovered from a serious endangered state through the implementation of sustainable use programs in Argentina, and represents nowadays a relevant economic resource for many human communities.

Short-Term Administration of Alibernet Red Wine Extract Failed To Affect Blood Pressure and To Improve Endothelial Function in Young Normotensive and Spontaneously Hypertensive Rats

As wine polyphenols were shown to possess many positive effects in mammals, including improvement of vascular function, this study investigated the effect of the Slovak Alibernet red wine extract (AWE) on blood pressure and vascular function in young normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats. Six weeks old, male, WKY and SHR were treated with AWE for three weeks at the dose of 24.2 mg/kg/day. Blood pressure (BP), determined by tail-cuff plethysmography, was significantly elevated in SHR vs. WKY and AWE failed to affect it. Lipid peroxidation was evaluated by determination of thiobarbituric acid-reactive substances. Vascular function was assessed in rings of the femoral artery using Mulvany-Halpern's myograph. Maximal endothelium-dependent acetylcholine (ACh)-induced relaxation was reduced in control SHR vs. WKY rats by approximately 9.3 %, which was associated with a significant decrease of its NO-independent component. AWE failed to affect maximal ACh-induced relaxation, both its NO-dependent and independent components, compared to controls of the same genotype. AWE however reduced lipid peroxidation in the left ventricle of both WKY and SHR and in the liver of SHR. In conclusion, three-week administration of AWE failed to reduce BP and to improve endothelial function in the femoral arteries of both genotypes investigated.

Antioxidant effect of apple phenolic on lipid peroxidation in Chinese-style sausage.

Chinese-style sausage is a very popular meat product obtained from a mixture of chopped pork meat, lard, salt, spices, additives (nitrate, nitrite, and antioxidants) and/or starter cultures. The antioxidative effect of apple phenolic on lipid oxidation in Chinese-style sausage compared with that of butylated hydroxy toluene (BHT) and ursolic acid were studied. Lipid oxidation was assessed through determination of thiobarbituric acid-reactive substances (TBARs) and volatile aldehydes. The content and composition of fatty acids in phospholipid were evaluated. At the optimum addition level, apple phenolic (0.5g·kg(-1) in total fat) was more effective at inhibiting lipid oxidation than BHT (0.15g·kg(-1) in total fat) and ursolic acid (0.5g·kg(-1) in total fat) in Chinese-style sausages during 120days storage. Moreover, apple phenolic exhibited stronger phospholipid protective capacity than ursolic acid and BHT at the end of storage. This study reveals a potential application of apple phenolic to enhance the oxidation stability of meat products during long storage.

Effect of moderate-intensity exercise on oxidative stress indices in metabolically healthy obese and metabolically unhealthy obese phenotypes in postmenopausal women

The aim of this work was to determine whether the level of oxidative stress induced by moderate-intensity exercise depends on obesity phenotypes: metabolically healthy but obese (MHO) and non-metabolically healthy obese (at-risk obesity; non-MHO). We performed the study on 161 postmenopausal women aged 50 to 60 years. A metabolically healthy nonobese (MH-NO) group (n = 73), an MHO group (n = 27), and a non-MHO group (n = 61) exercised on a cycloergometer for 30 minutes at 50% of their peak oxygen consumption and were evaluated for oxidative status by determination of thiobarbituric acid-reactive substances (TBARS) and serum antioxidant activity (AS). No difference was found in AS between the MH-NO group and the MHO group. The AS of the non-MHO group was significantly lower than that of the MH-NO group (P < 0.05) and that of the MHO group (P = 0.011). The insulin resistance index homeostasis model assessment was the only biochemical parameter that correlated with AS. After exercise, a significant increase in the TBARS concentration in all tested groups of women was observed, but differences in the increment of TBARS level between groups were not found. Antioxidant status in obese postmenopausal women depends on obesity phenotypes and is higher for women with the MHO than those with the non-MHO phenotype. Independently of obesity phenotype, obese postmenopausal women exposed to moderate-intensity exercise seem to be at similar risk for oxidative stress compared with their nonobese counterparts. We suggest that homeostasis model assessment be taken into account when planning physical exercise for obese people.

Determination of oxidative stress markers and serum cholinesterase among pesticide sprayers in southern Brazil

Small farmers generally spray pesticides manually and often do not use complete protective equipment. The standard test to detect pesticide exposure, which may be associated with toxicity, is the determination of serum cholinesterase, but in chronic exposure to low doses, this test is less sensitive. In this study, in a group sampled among pesticide sprayers without signs of intoxication, cholinesterase, thiobarbituric acid reactive substances (TBARS), catalase (Cat), and superoxide dismutase (Sod) activities were analyzed. Cholinesterase activity was only slightly lower in the farmer group in relation to the control group. However, TBARS and Cat activities were 3-fold increased in the farmers in comparison to the controls. Sod activity was similar in both groups. The group of pesticide sprayers that did not use the complete protective equipment presented a significantly higher level of TBARS than the group that used the complete protective equipment. Therefore, the determination of TBARS and catalase can be useful to identify individuals that are chronically exposed to low doses of pesticides.

Vanadium Pentoxide-Coated Ultrafine Titanium Dioxide Particles Induce Cellular Damage and Micronucleus Formation in V79 Cells

Surface-treated titanium dioxide (TiO2) particles coated with vanadium pentoxide (V2O5) are used industrially for selective catalytic reactions such as the removal of nitrous oxide from exhaust gases of combustion power plants (SCR process) and in biomaterials for increasing the strength of implants. In the present study, untreated ultrafine TiO2 particles (anatase, diameter: 30–50 nm) and vanadium pentoxide (V2O5)-treated anatase particles were tested for their cyto- and genotoxic effects in V79 cells (hamster lung fibroblasts). Cytotoxic effects of the particles were assessed by trypan blue exclusion, while genotoxic effects were investigated by micronucleus (MN) assay. In addition, the generation of reactive oxygen species (ROS) was determined by the acellular method of electron spin resonance technique (ESR) and by the cellular technique of determination of thiobarbituric acid-reactive substances (TBARS). Our results demonstrate that V2O5-treated TiO2 particles induce more potent cyto- and genotoxic effects than untreated particles. Further, acellular and cellular radical formation was more pronounced with V2O5-anatase than untreated anatase. Thus, data indicate that V2O5-treated TiO2 particles were more reactive than natural anatase and capable of inducing DNA damage in mammalian cells through production of free radicals.

Retinol increases catalase activity and protein content by a reactive species-dependent mechanism in Sertoli cells

Vitamin A (retinol) is widely used as an antioxidant in therapeutic interventions and dietary supplementations. However, the redox properties of retinoids have been the subject of intense debate in the last few years, as recent works observed deleterious effects caused by retinol supplementation in clinical trials. In the present work, we show that retinol treatment (7 μM, 24 h) led to catalase (EC 1.11.1.6; CAT) activation in cultured Sertoli cells by increasing its protein content in a reactive species-dependent manner. Retinol treatment also increased cell lipoperoxidation, assessed by determination of thiobarbituric acid-reactive substances (TBARS), and intracellular reactive species production, determined by the real-time dihydrochlorofluorescein (DCFH-DA) assay. However, no alterations on CAT mRNA expression (assessed by RT-PCR) were observed, indicating an effect independent of CAT gene-transcription regulation. Importantly, all the effects induced by retinol were inhibited by the antioxidant Trolox, a hydrophilic analogue of alpha-tocopherol. These results show for the first time that retinol increases CAT activity by a redox-dependent modulation of its protein content in a cell culture model. CAT activity or expression are widely used as indexes of oxidative stress in biological systems; since no changes in CAT mRNA expression were detected in these conditions, the use of CAT gene-transcription activation when assessing oxidative stress should be re-evaluated.

Anti-oxidative action of ent-kaurene diterpenoids

Nine ent-kaurene diterpenoids, leukamenin E, glaucocalyxin A, wangzaozi A, epinodisinol, epinodosin, rabdosin B, rabdosinate, lasiokaurin and oridonin, were separated from Isodon racemosa (Hemsl) Hara and Isodon japonica (Burm.f) Hara var. galaucocalyx (maxin). The protection against DNA damage induced by hydrogen peroxide in human peripheral blood mononuclear cells (PBMCs) and inhibition of lipid peroxidation in rat liver microsome were studied with comet assay and thiobarbituric acid reactive substances determination. All nine diterpenoids showed concentration-dependent protection in DNA damage in human PBMCs induced by 50 µM H2O2. The effects were similar and weaker than quercetin. The inhibitions of lipid peroxidation were obviously difference. Rabdosin B and oridonin were the strongest inhibitors, followed by lasiokaurin and wangzaozin A. Rabdosinate was the weakest and others were medium. The structure-activity relationship is discussed.

Antioxidant Activity of Propofol and Related Monomeric and Dimeric Compounds

This study was carried out to investigate the antioxidant activity of propofol (2,6-diisopropylphenol) and its related compounds, butylated hydroxyanisole (BHA), 2,6-dimethylphenol, 2,6-di-t-butylphenol, and their dimeric compounds. The degree of antioxidant activity was evaluated based on the degree of peroxidation induced with Fe-ascorbic acid in egg phosphatidylcholine through the determination of thiobarbituric acid-reactive substances (TBARS) formed during peroxidation. Their antioxidant activities were in the order of dipropofol>di(2,6-di-t-butylphenol)>diBHA>di(2,6-dimethylphenol). Dipropofol, a dimeric compound of propofol, showed the highest antioxidant activities. Dimeric compounds had higher activities than monomeric compounds, and the 1,1-diphenyl-p-picryhydrazyl-trapping ability of dimeric compounds was also greater than those of monomeric compounds (4-10-fold). These results suggest that dimeric phenols may increase their antioxidant activities along with increments in the conjugation system and play a inhibitory role in the propagation of free radical chain reactions.

Abstracts

Abstracts

Impaired high density lipoprotein antioxidant activity in healthy postmenopausal women

The high incidence of atherosclerosis in women after menopause is associated with a risk pattern including an increase in low density lipoprotein (LDL), even though high density lipoprotein (HDL) cholesterol levels tend to be maintained or slightly decreased. Since estrogens are considered potent antioxidants, an increase in lipid peroxidation and formation of reactive oxygen species would be expected after menopause. If HDL becomes oxidized, the ability to protect LDL against oxidation may be impaired. In postmenopausal women there are scarce reports concerning HDL oxidability and no data about its antioxidant activity. We studied copper-induced oxidation and conjugated dienes formation in HDL isolated from 58 women, 30 postmenopausal (PMW) and 28 premenopausal (PreMW). None presented diabetes or cardiovascular disease and none was receiving hormonal, hypolipidemic or antioxidant therapy either. In order to evaluate the effect of HDL on LDL oxidation we isolated LDL and HDL from the same subject and assessed copper-induced LDL oxidation in the presence of HDL, followed by thiobarbituric acid-reactive substances determination. Relationships with HDL chemical composition, α-tocopherol content, cholesteryl ester transfer protein (CETP) and paraoxonase activity (PON) were investigated. HDL chemical composition in PMW exhibited triglyceride enrichment when compared to PreMW (p < 0.05). α-Tocopherol content and CETP activity were similar in both groups. However, CETP activity correlated positively with HDL triglyceride and negatively with HDL cholesterol percentage (r = 0.44, p < 0.01 and r = −0.32, p < 0.05, respectively). Paraoxonase activity did not show differences between PMW and PreMW. When evaluating HDL oxidability, PMW revealed a shorter lag time in comparison to PreMW, even after adjustment for age, p < 0.05. Moreover, when the effect of HDL on LDL oxidation was evaluated, HDL from PMW showed a reduction in its ability to inhibit LDL oxidation, compared to PreMW (p < 0.05). In addition, the extent of inhibition of LDL oxidation by HDL was positively correlated with HDL resistance to oxidation (r = 0.27, p < 0.05). After women classification by paraoxonase phenotype, HDL ability to protect LDL against oxidation remained reduced only in PMW belonging to the PON QR phenotype, in comparison to PreMW QR. These results suggest that HDL from PMW exhibits impairment in its antioxidant ability, which is associated to a decreased HDL resistance to oxidation. In turn, this was related to triglyceride enrichment of HDL particles. All these alterations were independent from HDL cholesterol plasma levels.

The protective effect of taurine against gentamicin‐induced acute tubular necrosis in rats

Taurine, which is the major intracellular free beta-amino acid, is known to be an endogenous antioxidant and a membrane-stabilizing agent. In this study, we wished to know whether taurine altered the concentration of gentamicin in kidney tissue and could protect against gentamicin-induced acute proximal tubular injury. Wistar albino rats of both sexes were assigned to three groups, which all received one of the following daily intraperitoneal injections for 8 days: (i) 0.9% sodium chloride (NaCl) alone at the same volume as gentamicin treated rats (group C; n=8); (ii) 100 mg/kg/day gentamicin alone (group G; n=8, four male, four female); or (iii) 100 mg/kg/day gentamicin plus 7.5 ml/kg/day taurine (group G+T; n=9, five male, four female). Urine was collected for 24 h for the determination of urine volume and creatinine. Intracardiac blood was collected for blood urea nitrogen (BUN) and serum creatinine determination. The kidneys were removed, weighed, and the left kidneys were subjected to biochemical analysis for the determination of thiobarbituric acid-reactive substance (TBARS) and lactate levels, and glutathione peroxidase (Gpx) and superoxide dismutase (SOD) activities. The right kidneys were divided vertically in half. The upper halves were used for histopathological examination, by light and electron microscopy. The lower halves were used to detect the gentamicin concentration within the kidney tissue, by high-performance liquid chromatography (HPLC). Changes in body weight and normalized kidney weight were recorded. Taurine treatment reduced gentamicin-induced increases in serum creatinine, 24 h urine volume, BUN and tissue lactate and TBARS levels (0.57+/-0.02 vs 1.06+/-0.08 mg/dl, P<0.001; 9.00+/-1.46 vs 20.9+/-2.73 ml, P<0.001; 25.3+/-1.87 vs 54.1+/-6.99 mg/dl, P<0. 001; 2.56+/-0.10 vs 3.44+/-0.08 micromol/g wet tissue, P<0.001; and 66.4+/-3.41 vs 79.5+/-5.07 nmol/g wet tissue, P>0.05, respectively). Taurine reduced the accumulation of gentamicin within the kidney tissue (233+/-29 vs 494+/-93 microg/g wet tissue, P<0.05). Taurine treatment also prevented body weight loss due to gentamicin administration (17.8+/-1.64 vs -10.0+/-7.08 g, P<0.01) and normalized reduced Gpx and SOD activities (3.46+/-0.16 vs 2.37+/-0. 15 U/g wet tissue, P<0.01; and 15577+/-377 vs 12662+/-577 U/g wet tissue, P<0.01, respectively). Light microscopic examination of the renal tissues from gentamicin-treated rats revealed severe histopathological changes, whereas specimens obtained from taurine-treated rats revealed only mild changes. This finding was supported by electron microscopic examination. Our observations suggest that taurine treatment attenuates the accumulation of gentamicin within kidney tissue and counteracts the deleterious effect of gentamicin on renal tubular function. They may have potentially important clinical implications.

Interactions of Nitric Oxide with Lipid Peroxidation Products under Aerobic Conditions: Inhibitory Effects on the Formation of Malondialdehyde and Related Thiobarbituric Acid-Reactive Substances

Under aerobic conditions, exposure of peroxidized lipids to nitric oxide (NO) was found to result in a rapid decrease in the levels of thiobarbituric acid-reactive substances (TBARS). Addition of 10–100 μM NO to rat brain homogenates preincubated for 2 h at 37°C caused up to a 20% decrease in the levels of TBARS compared to controls. A similar inhibitory effect was observed on TBARS produced by Fe2+-induced decomposition of 15-hydroperoxyeicosatetraenoic acid (15-HPETE), due apparently to NO-induced decomposition of the hydroperoxide (ferrous oxidation/xylenol orange assay). Prostaglandin G2 (PGG2, 35 μM), as a model bicyclic endoperoxide, and malondialdehyde (MDA, 20 μM), the main component of TBARS, proved also susceptible to degradation by NO or NO donors (diethylamine NONOate, DEA/NO) at concentrations of 100 μM or higher in 0.05 M phosphate buffer, pH 7.4, and at 37°C, as indicated by the reduced response to the TBA assay. No significant effect on TBARS determination was caused by nitrite ions. These and other data indicate that NO can inhibit TBARS formation by decomposing primary lipid peroxidation products, chiefly 15-HPETE and related hydroperoxides, and, to a lesser extent, later stage TBARS precursors, including bicyclic endoperoxides and MDA, via nitrosation and other oxidative routes, without however affecting chromogenic reactions during the assay.

Oxypurinol administration fails to prevent free radical-mediated lipid peroxidation during loaded breathing.

The purpose of the present study was to determine whether it is possible to alter the development of fatigue and ablate free radical-mediated lipid peroxidation of the diaphragm during loaded breathing by administering oxypurinol, a xanthine oxidase inhibitor. We studied 1) room-air-breathing decerebrate, unanesthetized rats given either saline or oxypurinol (50 mg/kg) and loaded with a large inspiratory resistance until airway pressure had fallen by 50% and 2) unloaded saline- and oxypurinol-treated room-air-breathing control animals. Additional sets of studies were performed with animals breathing 100% oxygen. Animals were killed at the conclusion of loading, and diaphragmatic samples were obtained for determination of thiobarbituric acid-reactive substances and assessment of in vitro force generation. We found that loading of saline-treated animals resulted in significant diaphragmatic fatigue and thiobarbituric acid-reactive substances formation (P < 0.01). Oxypurinol administration, however, failed to increase load trial time, reduce fatigue development, or prevent lipid peroxidation in either room-air-breathing or oxygen-breathing animals. These data suggest that xanthine oxidase-dependent pathways do not generate physiologically significant levels of free radicals during the type of inspiratory resistive loading examined in this study.

Antioxidative resuscitation solution prevents leukocyte adhesion in the liver after hemorrhagic shock.

The generation of iron-dependent toxic oxygen radicals during the initial resuscitation from hemorrhagic shock was shown to be a relevant factor for the initiation of the inflammatory cascade. Therefore, this experimental study was designed to evaluate the effects of a deferoxamine-conjugated hydroxyethyl-starch solution (HES-DFO) on oxygen radical induced injury and microcirculatory alterations in the rat liver compared with resuscitation with regular hydroxyethyl-starch, lactated Ringer's solution (RL), or a gelatin-based solution. After hemorrhage and random assignment to 1 hour of blood-free resuscitation with the aforementioned solutions, hepatic microcirculation and leukocyte adhesion characteristics were assessed by intravital fluorescence microscopy in anesthetized rats. Oxygen radical activity was estimated by determination of glutathione levels in liver homogenate and determination of thiobarbituric acid-reactive substances in plasma as markers of lipid peroxidation. Resuscitation by HES-DFO resulted in restoration of hemodynamic parameters compared with gelatin-based solution and HES. The hepatic microcirculation was severely altered 1 hour after resuscitation from shock in all groups indicated by sinusoidal narrowing and reduced sinusoidal blood flow. HES-DFO, however, attenuated leukocyte adhesion and improved velocity index in sinusoids as well as sinusoidal perfusion. The shock-associated generation of oxygen radicals during resuscitation was prevented by HES-DFO as indicated by restored glutathione and reduced thiobarbituric acid-reactive substances. The results suggest that HES-DFO effectively reduces oxygen radical formation during the initial resuscitation period, thus, attenuating pathologically enhanced leukocyte adhesion and improving hepatic microcirculation.

The determination of TBA-reactive substances and alkenals in the presence of antioxidants.

This study investigated the inhibitory efficiency of all-rac-alpha-tocopherol, 2,6-ditert-butyl-p-cresole (BHT), and 6-hydroxy-2,5,7,8-tetramethyl-chroman-2-carbonic acid (Trolox) on determination of thiobarbituric acid-reactive substances (TBARS) and short-chain alkenals in rat liver homogenates. The concentration of TBARS was measured fluorophotometrically. Aldehydes were determined after derivatization with methylhydrazine by gas chromatography (GLC). The concentrations of alkenals and TBARS in liver homogenates were diminished when antioxidants were present during the sample preparation. It is suggested that in the absence of antioxidants the samples are autoxidized further during the preparative procedures. For the aldehyde determination all-rac-alpha-tocopherol was the most effective antioxidant to reduce the bias due to autoxidation, whereas for TBARS it was Trolox.

Relationships between lipid peroxidation and anoxia tolerance in a range of species during post‐anoxic reaeration

Peroxidation was studied in anoxically treated plant tissues and quantified as conjugated dienes/trienes in the total lipid fraction and as the production of thiobarbituric acid reactive substances (TBARS). Oxidative stress caused by re‐exposure of plants to oxygen led to an increase of conjugated diene/triene formation in rhizomes of Irisgermanica and roots of wheat (Triticum aestivum L.) and oats (Avena sativa L.), and after a long anoxic exposure (45 days) in the rhizomes of the very anoxia tolerant Iris pseudacorus. Second derivative (SD) spectrophotometry of the UV spectrum of lipid extracts confirmed the formation of dienes. However, determination of TBARS in Iris spp. showed no lipid peroxidation in the anoxia tolerant I. pseudacorus. In the rhizomes of the anoxia intolerant I. germanica, elevated levels of TBARS correlated positively with conjugated diene/triene formation. The results suggest that anoxic stress may induce qualitative changes in membrane lipids, as indicated by lipid peroxidation after restoration of aerobic conditions. The rate of lipid peroxidation correlated negatively with anoxic stress tolerance.